When do most eggs fail?

So, I'm on day 14. I started 13 eggs, I still have 13 eggs. All 13 are growing perfectly and 12 of the 13 were actively moving when I candled them today. I've got my hopes up! But should I? When do most of the egg failers start, right before hatch? Can most of my babies fully develop and die at the last few days??? :(

day ten may be a stop day you would see in the egg a blob, with no veins.

Day 16 the pointy part of the egg should be dark. (some people still see light in the point and think it is 2 air sacks, but light coming through point is fluid.) Don't give up on this egg though. the hatch of that egg may be delayed.

on day 19 if you candle, and you can see air sack, and just below air sack, and above the dark, you see fluid with no veins may be bad sign, but still wait it out. Look for veins in the area just below the air cell

At day 14 there's sure signs of healthy chickens in all 13 of my eggs, and as I said- active movement in 12 of the 13.. and even though the last one wasn't moving it still looked well developed and thick veins. I'm just wondering if I can expect a good hatch with most of them coming out well or if they're still likely to die from this point.